Modified phenolic resin toughened by phenoxy resin

Abstract

A modified phenolic resin which is toughened by phenoxy resin is disclosed. The modified phenolic resin is prepared by the following steps: mixing a phenoxy resin having a weight average molecular weight of 10,000-1,000,000 and phenol in a weight ratio of phenoxy resin:phenol=1.5:1-1:1 at an elevated temperature to form a glutinous mixture; mixing the glutinous mixture and an acid catalyst to obtain a viscous mixture having a relatively low viscosity compared to the glutinous mixture; mixing the viscose mixture and a resole type phenolic resin to form a modified phenolic resin, wherein the resole type phenolic resin has a solid content of 60-75 wt. % and a free aldehyde content of 5-10 wt. %, the amount of the acid catalyst mixed is 2-10 wt. %, and the amount of the phenoxy resin mixed is 3-25 wt. % based on the resole type phenolic resin.

What is claimed is: 
     
       1. A modified phenolic resin toughened by phenoxy resin, which is prepared by the following steps: a) mixing a phenoxy resin having a weight average molecular weight of 10,000-1,000,000 and phenol in a weight ratio of phenoxy resin:phenol=1.5:1-1:1 at an elevated temperature to form a glutinous mixture;   b) mixing the glutinous mixture of step a) and an acid catalyst to obtain a viscous mixture having a relatively low viscosity compared to the glutinous mixture;   c) mixing the viscose mixture of step b) and a resole type phenolic resin to form a modified phenolic resin, wherein the resole type phenolic resin has a solid content of 60-75 wt. % and a free aldehyde content of 5-10 wt. %, the amount of the acid catalyst mixed is 2-10 wt. %, and the amount of the phenoxy resin mixed is 3-25 wt. % based on the resole type phenolic resin.   
     
     
       2. The modified phenolic resin according to claim 1, wherein the phenoxy resin has a weight average molecular weight of 10,000-100,000. 
     
     
       3. The modified phenolic resin according to claim 1, wherein the phenoxy resin and the phenol are mixed in a weight ratio of phenoxy resin:phenol=1:1. 
     
     
       4. The modified phenolic resin according to claim 1, wherein the amount of the acid catalyst mixed is 5 wt. % based on the weight of the resole type phenolic resin. 
     
     
       5. The modified phenolic resin according to claim 1, wherein the amount of the phenoxy resin mixed is 10-15 wt. % based on the resole type phenolic resin. 
     
     
       6. The modified phenolic resin according to claim 1, wherein said acid catalyst is selected from the group consisting of p-toluenesulfonic acid, phenolsulfonic acid, benzoic acid and phosphoric acid. 
     
     
       7. The modified phenolic resin according to claim 1, wherein said phenol is selected from the group consisting of phenol, ortho-cresol, meta-cresol, para-cresol, dimethyl phenol, ethyl phenol, para-phenyl phenol, para-butyl phenol, para-pentyl phenol, bisphenol-A and meta-dihydroxyl benzene.